1. Field of the Invention
The present invention relates to an adjustable strap fastener of synthetic resin for adjustably interconnecting strap or belt ends on a bag or the like. More particularly, it relates to a sliding bar buckle having a strap retainer bar slidably mounted on a hollow or open rectangular frame for frictionally retaining a strap end.
2. Description of the Prior Art
Various adjustable strap fasteners or buckles have been proposed which may be manipulated to adjust the effective length of a strap on, for example, a bag. such fasteners are made of a plastic material formed into an integral molded structure which generally comprises a pair of laterally spaced legs, a grip base portion at one end of the legs, a connecting portion at the opposite end of the legs, and a plurality of cross bars disposed in between the grip base and connecting portions across between the legs. In use, one strap end portion is looped around one of the cross bars, passed under the connecting portion and secured in place as by stitching or rivetting. The other strap end portion which is adapted for length adjustment is looped around another cross bar, passed under the grip base portion and frictionally gripped therebetween against displacement. Such frictionally gripped strap tends to get loose when subjected to tensioning forces applied thereto. This tendency is less the smaller the gap between the grip base portion and the last-named cross bar, but the insertion or passage of the strap through the gap becomes more difficult.
An attempt has been made to overcome the foregoing difficulties, wherein a strap fastener includes an open rectangualr connector frame and strap retainer bar movably mounted on the frame. The frame has a grip base and a pair of laterally spaced legs extending from the grip base in a common direction and having a pair of transversely aligned oblong slots, respectively, extending longitudinally of the legs. The strap retainer bar has a pair of opposite arms loosely received in the respective oblong slots for sliding movement therein so that the strap retainer is movable toward and away from the grip base. In use, one end of a strap is looped around a central strap engagement portion of the retainer bar, and then passed under the base. When the strap is longitudinally tensioned, the strap retainer bar is displaced toward the base to press the strap against a strap bearing surface of the grip base. During that time, the strap retainer bar is likely to turn about the arms because the arms are loosely received in the slots. This angular movement of the retainer bar tends to reduce the holding force acting on the strap. This tendency will be greater where the central strap engagement portion has a circular, elliptical or rectangular shape in cross section, and the central strap engagement portion is disposed coaxially with the arms. In case the arms have a rectangular shape in cross section, angular movement of the strap retainer bar causes the arms to abut against the circumferential walls of the slots at diagonally opposite portions thereof with the result that the circumferential wall of the slots are deformed or damaged, thereby permitting rotation of the arms therein.